Two Lineages of oregana Genetic evidence for a Pleistocene separation into northern and southern glacial refugia

Chris Brinegar University of Maine Farmington

Photo: Humboldt-Del Norte Film Commission Oxalis oregana Nutt.

. Temperate coastal forests

. SW British Columbia to Central California

http://www.wildflowersearch.com/search?&tsn=29091 Oxalis oregana distribution in California

O. oregana was collected in seven redwood state parks and reserves throughout the coast redwood range. trnQ-rps16 Chloroplast (850 bp) intergenic spacers used psbD-trnT in this study Chloroplast (1400 bp) genome

psbJ-petA (700 bp) psbJ-petA intergenic spacer haplotypes

Single sequence haplotypes

“Mixed” sequence haplotypes petA-psbJ electropherograms

Haplotype A (single sequence)

single sequence

Haplotype F (mixed sequence)

double sequence psbJ-petA haplotype distribution trnQ-rps16 intergenic spacer haplotypes

Variable site Haplotype 212 267 281

Single sequence haplotype 1 T T A

2 T T A/T

Mixed sequence haplotypes 3 T T/G A/T

4 T/G T T trnQ-rps16 electropherograms

Haplotype 1 (single sequence)

Haplotype 2 (mixed sequence) trnQ-rps16 haplotype distribution Possible reasons for the double sequence results in the cpDNA of the “southern” lineage of O. oregana:

• PCR/sequencing artifacts • Contamination between samples • Duplication and divergence of cpDNA loci throughout the entire LSC region • Chimerism (mutation in a meristematic cell leading to cells in same having different cpDNA)

Chimerism is the cause of leaf O. corniculata O. regnellii O. tetraphylla variegation which is common in many species of Oxalis.

Chimerism cannot be propagated sexually.

If the southern lineage of O. oregana O. acetosella O. corymbosa O. oregana var. smallii is chimeric, then all propagation would be vegetative (rhizomes). Internal transcribed spacer (ITS) regions of nuclear rDNA

Six related “southern” genotypes and one “northern” genotype

Variable Position ITS ITS-1 ITS-2 genotype 49 77 93 99 114 126 136 168 223 226 394 422 469 572 591 594 S1 G C G G T – G G T A T C C A C T S2 A · · · · · · · · · · · · · · · S3 · · · · · · G/A · · · · · · · · · S4 · · · · · · · · · · · · T · · · S5 · · · · · · · · · · · · C/T · · · S6 · · · · · · · · · · · · · · C/T ·

N · T – T G A · T G C C T · G · C ITS genotype distribution

N/S1 genotype Chloroplast and nuclear loci analyses indicate two long-separated lineages of O. oregana

psbJ-petA trnQ-rps16 ITS

Migration of the southern lineage into the northern group was detected as was hybridization between the two (both at Jedediah Smith Redwoods State Park). The Klamath-Siskiyou ecoregion in southern Oregon and northern California is a center of biodiversity and a known glacial refugium for several and animal species.

Ribes bracteosum cpDNA haplotype distribution

Soltis et al. (1997) Pl. Syst. Evol. 206: 353-373 http://kswild.org/ksregion Is it more than coincidence that the southwestern edge of the K-S ecoregion splits the northern and southern lineages of O. oregana?

Klamath-Siskiyou ecoregion PC

JS

PC The mountains that form the boundary of the Klamath River and Redwood Creek watersheds could be the major barrier between the northern and southern O. oregana lineages. HU This suggests that ancestral O. oregana separated into at least two glacial refugia during the Pleistocene: a “southern” refugium (south of the K-S region) a “northern” refugium (either in the K-S region or in a more northern location) Neighbor-joining tree of ITS sequences

The “northern” ITS sequence (N) is 100% homologous to the only O. oregana sequence in Genbank (from an accession in State).

This suggests a rapid post-glacial expansion of a bottlenecked northern lineage, either northward from the K-S refugium or southward from one in Oregon, Washington or BC.

The southern lineage had room to expand and diverge during the glacial periods.

The fact that the northern lineage has an ITS sequence more related to O. acetosella than to the southern lineage indicates a very long period of separation between the lineages. Is the difference between the lineages enough to designate subspecies?

Requirements for subspecies designation:

• Geographically separate (except at hybridization zones)

• Genetically distinct (application of the 75% rule)

• Capable of hybridization

• Morphologically distinct Future research

• Genetic analysis of OR, WA, BC populations

• Analyze more Humboldt Co. populations to define the dividing line between lineages

• Test chimerism hypothesis

• Assess morphology of northern and southern groups for possible sub-species designations

• Check other redwood forest species for similar north/south differences Acknowledgements